Lift trucks are designed in a variety of configurations to perform a variety of tasks. One problem with lift trucks is that they can oscillate or vibrate about any of the X-axis, Y-axis and Z-axis (see FIG. 1). For example, when an operator stops the truck abruptly or abruptly changes direction, or both, torsional vibrating motion about the Z-axis (also referred to as yaw) can be felt by the lift truck operator. The vibrations can be more noticeable when the lift truck's mast is vertically extended. While such torsional motion will not tip the truck, the motion can be disconcerting to the operator. Normally an operator will slow down and allow the vibrating motion to naturally dissipate before resuming travel. These unwanted vibrations can reduce the efficiency of the operator and the overall productivity of lift truck operations.
Another problem seen by lift trucks traveling throughout a facility is that they can encounter debris on the floor and uneven floor surfaces. These can take the form of expansion joints, cracks in the floor surface or man-made objects such as ramps going between buildings or into tractor trailers. Tire irregularities and/or the floor can also cause periodic vibrations that can be transmitted throughout the truck's frame.
The vibrations caused by the floor condition can diminish the effectiveness and/or accuracy of sensory equipment on the truck and may necessitate that the truck be operated at slower speeds to reduce the effects of the floor conditions. Slower operating speeds can equate to an undesirable reduction in overall equipment productivity.
Most previously used methods to dissipate vibrations have only attempted to address longitudinal vibrations, and do not address torsional vibrations. Methods that have attempted to address torsional vibrations add unnecessary complexity to the lift truck by decoupling the mast from the carriage. This adds cost and weight, and further areas for mechanical issues.
If the vibrating motion of the truck can be mitigated or even cancelled, the truck would then be capable of traveling faster without the potential damage to components or loss or degradation of truck data, along with a more comfortable ride for the operator.
What is needed is a lift truck configured to improve mitigation of vibrations about the Z-axis, thereby providing a more comfortable ride for the operator and improving productivity.